suggestions with credit card Terminal

First, this probably isnt the right area to post this. Sorry, but im desperate. You guys seem to be good with with computer related stuff. We have a credit card processing unit and everything was working good until we went from roadrunner cable to DSL. Our credit card machine now will NOT connect through ethernet..only dial up. We have checked our router that it is plugged into and the port is lit so we know its connected. All of our desktops connect to the internet all day long without issues .Anyone have any ideas!?!? Thanks in advance!